Political leaders at every level are demanding we evaluate and pay teachers based on student test scores and value-added statistical formulas. If that turns out to be a bad strategy, the long-term ramifications for the nation could be staggering.

"Now's the time to transcend the usual debates over how to make our schools better and our teachers more effective - and break free of the myths that keep us fighting 20th century battles. Instead we need to look hard at the realities, framed by research evidence as well as the challenges teachers face everyday"

Amazing, but as it turns out, quite logical. "The brain has very specialised modules for different tasks, like language processing and spatial recognition. It stands to reason that two similar tasks are much harder to do simultaneously, because they're using similar bits of tissue."